Table 2 Incidence and prevalence rates of laboratory-confirmed influenza in children

Community-based estimates

Van der Zalm, et al., 2009 [50]

The Netherlands

< 1 year

Community

October 2003 – September 2006.

Prevalence rate: influenza was detected in 2.7% of respiratory samples

Follow-up: until infants reached 1 year of age.

Annual incidence rate: 62 per 1,000^a

Heikkinen et al., 2004 [35]

Finland

≤ 13 years

Community

9 October 2000 – 20 May 2001 and 1 October 2001 – 19 May 2002.

Influenza-season incidence rate per 1,000 children:

All ages combined: 167,^b

Age < 3 years: 179,

Age 3-6 years: 175,

Age 7-13 years: 142.

Health care setting-based estimates

Ploin et al., 2003 [43]

France

0-11 months

Paediatric ED

4 weeks of local influenza epidemic peak (weeks 3-6 in 2002)

Prevalence rate:

Total: 33%,

Aged 0-2 months: 31%,

Aged 3-5 months: 27%,

Aged 6-8 months: 30%,

Aged 9-11 months: 40%.

Ploin et al., 2007 [36]

France

< 36 months

Paediatric ED

4 weeks of local influenza epidemic peak (weeks 3-6 in 2002)

Prevalence rate: 49%

Ehlken et al., 2005 [45]

Germany

0-36 months

PCP, paediatric hospital

1 November 1999 – 31 October 2001.

Annual incidence rate of LRTI associate with influenza: 1.1 per 100 children-years.

Heinonen et al., 2010 [42]

Finland

1-3 years (mean age: 2.4 years)

Primary care clinic

Two local influenza circulation seasons: 14 January – 9 April 2008 and 7 January – 26 March 2009.

Prevalence rate: 24.7% of children tested positive for influenza.

Follow-up: 21 days.

Esposito et al., 2011 [37]

Italy

< 14 years

PCP (with community “base”)

1 November 2008 – 30 April 2009.

Influenza-season incidence rate: 96.4 per 1,000 children.

Principi et al., 2003 [48]

Italy

< 14 years

PCP and ED

1 November 2001 – 30 April 2002.

Prevalence rate: 9.3%, (virology or PCR),

Principi et al., 2004 [38]

Including:

8.7% of children seen in EDs and

11.5% of children seen by PCPs.

Bosis et al., 2005 [46]

Italy

< 15 years

ED

1 November 2002 – 31 March 2003.

Prevalence rate; 15.3% (by PCR).

Esposito et al., 2005 [47]

Italy

< 15 years

ED

1 November 2002 – 31 March 2003.

Prevalence rate: 15.4% (by PCR).

Sanni et al., 2004 [44]

France

≤ 15 years

Hospital

37 days of local influenza epidemic (1 January – 6 February 2002)

Prevalence rate:

Total: 51.8%,

Aged 0-1 year: 42.4%,

Aged > 1 and ≤ 3 years: 68.9%,

Aged > 3 and ≤ 5 years: 41.2%,

Aged > 5 and ≤15 years: 36.8%.